This application is based on and claims priority under 35 U.S.C. xc2xa7119 with respect to Japanese Application No. 2000-351656 filed on Nov. 17, 2000, the entire content of which is incorporated herein by reference.
The present invention generally relates to a vehicle motion control device. More particularly, the present invention pertains to a vehicle motion control device for supplying hydraulic pressure generated by an automatic hydraulic pressure generator, which is adapted to generate the hydraulic pressure irrespective of operation of a brake pedal, to a wheel cylinder via hydraulic pressure control valves. The vehicle motion control device of the present invention is applicable to a brake steering control device and a traction control device.
Japanese Patent Laid-Open Publication No. H02-241863 discloses a vehicle motion control device. In this known device, when the driving wheels are spinning, a master cylinder hydraulic pressure is generated by a vacuum booster which is automatically operated by a solenoid valve for braking the spinning wheels irrespective of the operation of a brake pedal. Thus, traction control is performed.
However, with the foregoing vehicle motion control device, abnormalities involving the automatic hydraulic pressure generator, including the master cylinder, the vacuum booster and the solenoid valve, are not detected. Thus, traction control may not be appropriately carried out under abnormal conditions of the hydraulic pressure generator.
A need thus exists for a vehicle motion control device which is able to detect an abnormality with respect to the automatic hydraulic pressure controller having a master cylinder, a booster for boosting the master cylinder, and a booster actuator for actuating the booster irrespective of operation of a brake pedal and for performing an appropriate transaction or control even when an abnormality is detected or exists.
According to one aspect of the invention, a vehicle motion control device includes a wheel cylinder equipped on a vehicle wheel for providing braking torque, and an automatic hydraulic pressure generator including a master cylinder, a booster and a booster actuator. The master cylinder supplies a master cylinder hydraulic pressure to the wheel cylinder, the booster boosts actuation of the master cylinder in accordance with operation of a brake pedal, and the booster actuator actuates the booster irrespective of the operation of the brake pedal and generates the master cylinder hydraulic pressure in the master cylinder. A hydraulic pressure control valve is disposed between the automatic hydraulic pressure generator and the wheel cylinder for controlling a brake hydraulic pressure of the wheel cylinder, and a control mechanism controls the booster actuator of the automatic hydraulic pressure generator and the hydraulic pressure control valve in accordance with the running condition of the vehicle and performs an automatic pressure increase control to the wheel cylinder. An abnormality detecting mechanism detects an abnormality of the automatic hydraulic pressure generator, and an abnormality transaction mechanism performs a predetermined transaction with respect to the automatic pressure increase control by the control mechanism when the abnormality detecting mechanism detects the abnormality of the automatic hydraulic pressure generator.
According to another aspect of the invention, a vehicle motion control device includes a wheel cylinder operatively associated with a vehicle wheel for applying a braking force, and an automatic hydraulic pressure generator including a master cylinder, a booster and a booster actuator. The master cylinder supplies a master cylinder hydraulic pressure to the wheel cylinder, the booster boosts actuation of the master cylinder in accordance with operation of a brake pedal, and the booster actuator actuates the booster irrespective of the operation of the brake pedal and generates the master cylinder hydraulic pressure in the master cylinder. A hydraulic pressure control valve is disposed between the automatic hydraulic pressure generator and the wheel cylinder for controlling a brake hydraulic pressure of the wheel cylinder, and a controller controls the booster actuator of the automatic hydraulic pressure generator and the hydraulic pressure control valve in accordance with a running condition of the vehicle and performs an automatic pressure increase control to the wheel cylinder. A deceleration detector detects or estimates a vehicle deceleration of the vehicle, and a hydraulic pressure detector detects the master cylinder hydraulic pressure. A mechanism is provided for determining whether at least one of the deceleration detector and the hydraulic pressure detector is operating normally. An abnormality detector detects an abnormality of the automatic hydraulic pressure generator only when it is determined that at least one of the deceleration detector and the hydraulic pressure detector is operating normally, and an abnormality transaction mechanism performs a predetermined transaction with respect to the automatic pressure increase control by the controller when the abnormality detecting mechanism detects the abnormality of the automatic hydraulic pressure generator.
Another aspect of the invention involves a method of controlling vehicle motion in a vehicle that includes a wheel cylinder operatively associated with a vehicle wheel for applying a braking force to the wheel, an automatic hydraulic pressure generator having a master cylinder, a booster and a booster actuator, with the master cylinder supplying master cylinder hydraulic pressure to the wheel cylinder, the booster boosting actuation of the master cylinder in accordance with operation of a brake pedal and the booster actuator actuating the booster irrespective of operation of the brake pedal to generate the master cylinder hydraulic pressure in the master cylinder, and a hydraulic pressure control valve disposed between the automatic hydraulic pressure generator and the wheel cylinder for controlling a brake hydraulic pressure of the wheel cylinder. The method includes controlling the booster actuator of the automatic hydraulic pressure generator and the hydraulic pressure control valve based on a running condition of the vehicle to perform an automatic pressure increase control to the wheel cylinder, detecting an abnormality of the automatic hydraulic pressure generator, and performing a predetermined operation with respect to the automatic pressure increase control when an abnormality of the automatic hydraulic pressure generator is detected.